Electromagnetic means for feeding a ferromagnetic charge to a furnace



1947- H. A. STRICKLAND, JR

ELECTROMAGNETIC MEANS FOR FEEDING A FERROMAGNETIC CHARGE TO A FURNACE Filed May 29, 1943 A m P -INVENTOR Harold w .StriddandJr. paw

A TTORNE V lar highly conducting metal;

Patented Feb. 4, 1947 ELECTROMAGNETIC FERROMAGNETIC NACE ANS FOR FEEDING A CHARGE TO A FUR- Harold A. Strickland, Jr., Detroit, Mich, assignor, by mesne assignments, to The Budd Company,

Philadelphia, vania Pa., a corporation of Pennsyl- Application May 29, 1943, Serial No. 489,082

5 Claims. 1

This invention relates to feeding apparatus forv ferromagnetic articles with particular application -to utilizing induction heating means.

The important'objects of the present invention may be summarized as follows: to provide magnetic means for feeding the charge or work piece to a furnace in stepped intervals; to provide feeding means for moving articles to a furnace tobe heated in which the movement of the feeding means is ontrolled by the movement of the charge after expulsion from the furnace; to provide timing means for feeding apparatus which is electrically controlled by delayed action mechanism; to provide in combination with step bystep feeding apparatus, heating means automatically timed by the heating temperature of the charge; to provide magnetic holding means for a charge in a furnace which permits release of the charge without external modification of the magnetic action of the holding means when the charge is heated to the degree desired; to provide a gravitational feed for a furnac with charge holding means and heating means which functions automatically whenever charges are placed in the feeding, holding and heating apparatus and which can not properly function without the proximity of the charge. Other objects will appear on consideration of the specific embodiment of the invention which may be preferred as hereinafter described and as shown in the accompanying drawing in which Figure l is a. diagrammatic showing partly in section of the feeding, holding and heating apparatus combined with the various controlling circuits and switches:

Figure 2 is a section of Figure 1 taken along line 2-2;

Figure 3 is a detail showing one mode of enclosing the end of the core yoke in copper or simi- Figure 4 shows another means of enclosing the holding core yoke; and

Figure 5 illustrates a modified delayed action type of circuit control switch.

Referring to the drawing, Figure 1 illustrates a non-magnetic chute ID in which various articles to be heated l I are fed by any appropriate means. These articles or work pieces, referred to generally as charges, maybe of a. miscellaneous type of articles, such as projectiles, formed of ferromagnetic substances such as iron, steel, nickel, cobalt or mixtures of these ferromagnetic substances with paramagnetic substances. charges when placed in the upper end of chute Ill normally move by gravity to the'base l2 of the chute, terminating in the quench tank l3 containing appropriate quenching fluid H. Interposed between the upper end of the chute as shown and the lower end I 2 are a series of electromagnet elements preferably in three units, the initial feed- The ing unit IS, the final feeding unit I 6 and the holding unit l1, these units being placed in the series mentioned with the holding unit at the base. Each unit consists preferably of four electromagnet elements It, indicated in Figure 2, of the drawing, spaced about thechute in generally parallel relationship thereto. These elements include the magnetizing coils lia, l6a and lla enclosing U-shaped magnet cores lib, llib and Nb. The terminals of the cores are positioned closely adjacent the chute III as illustrated in Figure 1. It thus appears that it charges ll, 20 and 2l are positioned as shown in Figure 1, the charge ll being between the core terminals l5b, the charge 20 between the core terminals lfi'b and the charge 2l between core terminals l'lb, these various charges complete with the adjacent cores a practically closed magnetic circuit so that'as the vari ous coils l-5a, I61: and l'la are energized the magnetic action will hold the charges approximately in the position as shown, it being understood that the number of turns of the'windings of the coils together with the dimensions of th cores and the amount of current flowing in the coils is such as to obtain the mentioned holding effects.

Within the chute area enclosed by electromagnet li a heating coil 22 is positioned exterior to but adjacent the chute surface, the circular section of the conductor indicating diagrammatically the tubular shape adapted for cooling fluids. The ends of this heating coil 22 are attached to the secondary 23 of a heating coil transformer 24 theprimary 25 of which is connected to appropriate alternating or intermitting current of desired frequency. As is well known in this art, heating is produced by inductive action of the coil 22 on the charge 2|. During the heating period the holding coil l1 magnetically retains the charge 2| in position to be heated by the heating coil' 22. For this purpose direct current preferably is supplied the magnet l'l through variable control resistance 26 from source points 21.

Electromagnets l5 and l 6 are connected in parallel with an appropriate power source 28 and 23 which may be direct or alternating current. As illustrated, points 30 and 3| of magnets l5 and ii are connected directly to power source 28 while points 32 and 33 of these magnets are connected to power source 29 through a magnetically controlled switch hereafter referred to as the magnet switch 34. This switch consists of a movable arm 35 pivoted at 36 and normally held in the lowerthe opening on.

extends into the chute an amount sumcient to 3 or coil lea. These contacts are elongated, as shown, andhave rounded ends and are placed parallel and in relatively close proximity to each other with the ends reversed,and in such relation to the movable arm of the switch 3d that when the arm moves between its lower and upper limits it successively engages the contact 33, both contacts 3B and 39 as shown in dotted outline, and

finally contact 38 only. It thus appears that when power is led into the feeding circuit from points 28 and 23 with the switch arm 35 in the hopper or travelling belt arrangement charge 2! is carried down to the bank of magnets, power switch 2a; being opened and power switch 27a and the heating circuit being closed, the charge moves to a point opposite the magnet H where it is inductively heated. As the temperature apposition shown in fullclines, only magnet 38 is energized; in the position of the arms shown in 'dotted'outline, both coils a and Ma are ener-.

gized; while in the uppermost position with the arm contacting the contact 38 only, the coil l5a only is energized. Resistance coils 42 and 43 preferably are utilized for bridging themagnet coils l5a and 16a, respectively, so as to limit the magmoving the arm 35 of magnet switch 35 the same being generally indicated by the numeral '45. This control switch operates in conjunction with a solenoid 46 positioned above the magnet switch arm 35, the core 41 being movable within the solenoid and having a lower end 48 pivotallysecured to thearm intermediate its length so that upward movement of the core is accompanied by corresponding upward movement of the arm 35. This upward core movement is brought about by energization of theisolenoid through action oithe control switch 65.

The switch includes-two eleni r-ints, the-665 Q I tact arm 50 pivoted on fixed support 5| and spring held in downwardposition by-aleaf spring 52, and a contact e1ement 53,.co prising a cylin-:-;.--

der or disc having on its peri sector 56 and a metallic con ct two sectors being contiguoussector being 'normally in coma held arm 59f The contact element 53 isjmounted for limited rotation on the support 56 so that rotation of the cylinder 53 in the, direction indiery nf'insulation sector; v the hefsinsulator cated by-the arrow causes contact to be made.

between the metallic sector 55 of the cylinder and the switch arm 5%. Such contact will of course close the electric circuit through flexible connector 68a, wires 5i and 58, through solenoid as to the power source 28 and 29 thereby energizing the solenoid and causing the upward movement of the core ill. There is attached also to the pivot pin ea oi the cylinder 53 and movable with such cylinder a projectingcontact pin to which extends from the pivot pin 53 to the interior of the chute it at the lower end 82 thereof, this lower end having a section on the side of the chute adjacent the control switch cut away to form As illustrated the contact pin engage a falling charge so that the charge by its movement forces the contact pin downwardly against the action of the pin holding spring e2 until the pin end is clear of the moving charge,

the pin thereupon swinging back into the full line position as shown. It is apparent that this forcing movement of the pin 89 by the moving charge that the charges tend to move downwardly toit'h the-spring 3 proaches' the recalescence point the magnetic holding efiect of magnet ll rapidly diminishes toward zero and the charge is released and falls by gravity toward the quench tank l3. In the meantime while charge M is being heated switch ,28a supplying power from source 28-29 is closedv thus energizing magnet i 6, and one or more addi-,

tional charges are permitted to fall through the chute, the leading charge 20 being retained opposite the poles or energized magnet it, thus holding charge H and other charges which maybe behind this charge in a static position in the chute.

the circuit through the solenoid 46. Thereupon the arm 35 of the magnet switch 38 moves upwardly over the contact plates 38 and 33, at the limit of its movement the arm contacting only with plate 38. In the upward movement of the arm 35 it is observed that at the midpoint both plates 83 and 33 are engaged so that both coils i5 and is are simultaneously energized thus magnetizing not only magnet l6 but additionally magnet I5 so that the charge it is retained in position by magnet" force efiective prior to the opening of the circuit of magnet it. Accordingly when the arm 35 moves clear of plate 39, permitting magnet as to be de-energized, charge H is retained in position by magnet it but charge 20 is free to fall into the magnetized region of magnet H where it is held for a heating treatment by coil 22.

Charge ii is held in its position opposite magnet 55 for a brief interval only since the circuit of magnet 65 is closed only during the energizetion of solenoid as and this energization in turn is dependent upon the movement of control switch arm 68. Therefore, as soon as the charge 25 has moved past the arm 68, the same will, under the pressure of spring 62, move again upwardly to a horizontal position, as limited by the top edge of the gap ti. This of course breaks the solenoid circuit, de-energizing coil is and permitting charge it to fall until held by the magnet it re-energized by the downward movement of magnet switch arm 35. At the same time a new charge i i moves into the space opposite the poles of magnet l5. It is evident that as soon as the 1 above cycle of movement is once established it will continue'automatically as long as additional charges are fed into the chute.

.With certain masses of charges the time interval of action control switch 85 is too short and hence it may be desirable to slow down the return movement of the arm St of this switch.

Figure 5 illustrates a slow motion device for accomplishi'ng this result and shown in substitution through gravitationai pull. r.

actuate s N. The piston head contains axial openings ill of diminished diameter so that rapid movement of the piston which contains air or other gas is delayed unless the piston is moved with considerable force. The free end of the piston rod it has a pivot connection w th and of arm "it, the other end of which is fixed to the shaft 59 movable with a cylinder at of the control switch.

'With this construction when the charge 29 moves past the arm tip of arm to the piston is suddenly forced upwardly, the weight of the charge being suflicient to overcome the resistance of the air moving through apertures l8 oi the piston lb. On release of the arm til however the only pres sure being exerted in the cylinder ll is the weight of the piston and associated parts which com. presses the gas beneath the piston, causing it to flow upwardly through apertures it until the pis ton is at the downward end oi the cylinder and arm Bil is at its normal upward level. Accord ingly the time period of contact of control arm 58 and metallic sector is increased thm hi creasing the holding period oi magnet It is pointed out that the heating coil 22 produces flux which includes the pole tips of the core Nb and possibly also 96h. Consequently these poles will be subjected to the heating ac tion of the inductive circuit. Since this would be undesirable means are provided as illustrated in Figures 3 and e for short circuiting calm cur= rents formed in the pole tips by means oi a shell of copper or other metal which encloses the pole tips or the whole core. in the term of nttach-= ment shown in Figure 3 the copper shell Bill is either electrically applieolto the core through out its entire length or is closely fixed to the steel or iron core til and the ends closed by copper disks 82 attached by silver solder as indi= cated. In the alternative arrangement of Fig ure 4, a cap tube 83 is applied to the ends only of the yoke of the core 8!] and secured thereto by any appropriate means.

In describing the heating, holding andieeding including electro-maanets spaced along the chute at points displaced from the heating means, switch means for energizing said magnets in suc cession toward said heating means, and actuating means for operating said switch means.

2. In charge feeding apparatus, a non-magnetic chute, heating means for a ferromagnetic charge, retention means for holding the charge at the heating means, and feeding means for supplying a charge intermittently to said heating means, said feeding means including electro-magnets spaced along the chute at point displaced from the heating means, switch means for energizing said magnets in succession toward said heating means, and actuating means for operating said switch means, said actuating means being operated by a charge subsequent to release after being heated to recalescehce by said heating means.

' 3. In charge feeding apparatus, a non-magnetic chute, heating means for a ferromagnetic charge in said chute, retention means for holdin the charge at the heating means, and feeding means to? supplying a charge intermittently to said heating means, said feeding means including elec= taro-magnets spaced along the chute at points dis placed from the heating means, switch means 1 for energizing said magnets in succession toward unit adherence has been, made to specified ele= -movement of the charge for timing the move ment of the feed apparatus in its broader aspects manual or other means may be employed for the ieeding operation. While I have indicated direct current as desirable tor the holding unit I"! it may be possible under certain circumstances to employ alternating current. The time delay means of Figure is of course merely illustrative as in substitution any of the well known types of time delaying mechanism may be employed. Other modifications will be apparent to those skilled in this particular art and hence no limitations are implied other than those required by the scope of the claims hereto appended.

What is claimed is:

1. In charge feeding apparatus, a non-magnetic chute, heating means for a ferromagnetic charge in said chute, independent retention means for holding the charge at the heating means, and teedins means for supp y c a charge intermittently to said heating means, said teedins means said heating means and charge actuated means for operating said switch means.

a. in charge feeding apparatus, a non-magnetic chute, heating means a ferromagnetic charge in said chute, retention means as holding the charge at the heating means, and feeding means for supplying a charge inte .ttently to said heating means. said feeding means including elec tro-magnets spaced along the chute at points di placed from the heating means, switch means for energizing said magnets in succession and charge actuated means for operating said switch means, said charge actuated means including a time delay mechanism.-

5. In charge feeding apparatus, a non-magnetic chute, heating means for a ferromagnetic charge in said chute, retention means for holding the charge at the heating means, and feeding means for supplying a charge intermittently to said heating means, said feeding means including electromagnets spaced along the chute at points displaced from the heating means, switch means for energizing said magnets in succession, and actuating means for operating said switch means,

' said actuating means including normally open make and break electrical contacts and an arm extending into said chute whereby movement of a. charge through the chute moves the arm to close said contacts.

HAROLD A. STRICKLAND. JR.

REFERENCES CITED The following references are of record in the ills of this patent:

UNITED STATES PATENTS Number Name Date 97,811 Dailey Jan. 1, 1929 1,747,934 Heidenhain Feb. 18, 1930 7 04 Knerr Oct. 28, 1930 2,059,300 Adams Nov. .3, 1936 1,412,484 Mordey Apr. 11, 1922 1,932,423 Sessions Oct. 31, 1933 ,1 ,1 5 Thullier June 1, 1915 FOREIGN PATENTS Number Country Date 150,486 British Sept. 9, 1920 British OI 1926 

